Township Board Gets a Weed Update

Posted May 15, 2017

Clark Lake has declared war on the advance of hybrid Eurasian water milfoil (HEWM). Why? Where left unchecked, HEWM can diminish recreational use of a lake, destroy wildlife habitat, and negatively affect property values. A majority of Clark Lake lakefront property owners petitioned Columbia Township to establish a special assessment district (SAD) to deal with the problem. The SAD allows treatment of HEWM wherever it exists in the lake and covers the cost of the project through the property taxes of lakefront landowners.

PLM Lake & Land Management (PLM) has been contracted to treat Clark Lake. At tonight’s meeting of the Columbia Township board, Trustee Flip Reynolds and Treasurer John Calhoun, both Clark Lake residents, discussed the state of the battle. In their presentation to the board, John Calhoun and Flip Reynolds described the challenge–Clark Lake’s version of HEWM has not been permanently eradicated by the current product (Renovate). That has lead PLM to look into other solutions from Sepro, a company that develops treatment products, including a new one called Procellacor. In this video, John Calhoun starts by reading an email from PLM’s Steve Hanson. Flip Reynolds then follows up.

To understand the challenge, a chain reaction can happen when Eurasian milfoil enters a lake. The invader mates with the native plant. The resulting hybrid mates with other hybrids and native plants. Or varieties of hybrids travel from lake to lake by boat or other means. Darwinian evolution results in improved sustainability and thus, a greater opportunity to procreate, and become immune to threats like treatment programs. Take that cycle through several iterations, and you can see the challenge in knocking off an invasive species.

During the 2016 season, PLM treated about 30 acres of HEWM with Renovate (active ingredient, triclopyr). According to PLM’s Steve Hanson, “initial results were good, but follow up surveys indicated regrowth of HEWM by summers end.” Steve noted “these results were concerning to me, as I expected our treatments to have at least season-long effects, if not multiple years.”

At the Township meeting (and in the video), John Calhoun referred to a study performed by Sepro. To focus treatment on Clark Lake’s version of HEWM, samples were sent to lab for testing. The Clark Lake plants were exposed to three herbicides—triclopyr, 2,4-D, and Fluridone. The lab reported the Clark Lake samples were not susceptible to 2,4-D. Some samples were somewhat vulnerable to triclopyr, while others were not affected. The labs results showed all Clark Lake HEWM samples were susceptible to Fluridone, a more expensive product.

Steven Hanson concludes “it is not prudent to continue the triclopyr treatment.” As noted in the video, PLM suggests a new entry into the field, Procellacor, has promise. Logistical issues prevent its use in 2017, among them the state hasn’t approved it yet. With only four acres of treatment anticipated in 2017, the “savings” could be applied to a more effective program in 2018.

As more information becomes available, expect updates on this website.